Refactor scheduler.py to use the application-level pooled DatabaseClient

Replace the per-invocation DatabaseClient creation in
run_scheduled_analysis() with the shared pooled client from
SPARC.auth.get_db_client(). This avoids creating a new database
connection on every scheduler tick, which could exhaust the connection
pool under load.

Key changes:
- Import get_db_client from SPARC.auth instead of DatabaseClient
- Remove manual connect/initialize_schema/close calls
- Remove unused SPARC.config import

Closes leeworks-agents/SPARC#1658

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

SPARC/scheduler.py

@@ -2,14 +2,17 @@
 
 Uses APScheduler to periodically re-analyze tracked companies and
 detect significant changes in patent counts.
+
+The scheduler reuses the application-level pooled DatabaseClient
+(from ``SPARC.auth``) instead of creating its own connection, which
+avoids exhausting the database connection pool under load.
 """
 
 import logging
 import os
 
-from SPARC import config
 from SPARC.analyzer import CompanyAnalyzer
-from SPARC.database import DatabaseClient
+from SPARC.auth import get_db_client
 
 logger = logging.getLogger(__name__)
 
@@ -21,10 +24,13 @@ CHANGE_THRESHOLD_PERCENT = int(os.getenv("CHANGE_THRESHOLD_PERCENT", "20"))
 
 
 def run_scheduled_analysis() -> None:
-    """Re-analyze all tracked companies and check for significant changes."""
-    db = DatabaseClient(config.database_url)
-    db.connect()
-    db.initialize_schema()
+    """Re-analyze all tracked companies and check for significant changes.
+
+    Uses the shared pooled DatabaseClient from ``SPARC.auth.get_db_client()``
+    rather than creating a disposable connection, so the scheduler participates
+    in the same connection pool as the rest of the application.
+    """
+    db = get_db_client()
 
     tracked = db.list_tracked_companies()
     if not tracked:
@@ -74,7 +80,6 @@ def run_scheduled_analysis() -> None:
         except Exception as e:
             logger.error("Error analyzing tracked company %s: %s", name, e)
 
-    db.close()
     logger.info("Scheduled analysis complete")